1. Field of the Invention
The present invention is directed to an apparatus and method for use in medical injection technology. More particularly, the present invention is directed to improved hypodermic syringe assemblies and methods for using the same.
2. Description of the Related Art
For generations, people all over the world have received injections (or fluid withdrawals) utilizing a piston driven device commonly referred to as a hypodermic syringe. Hypodermic syringe designs have not really changed much since their first inception in which a plunger formed from a piston and piston rod is manually operated to drive fluid, from a cylindrical chamber in the syringe into, or out of, a living body through a needle.
Similarly, unchanged is the way that a dosage of medicine is stored such as in an ampoule or a vial in which the period of drug shelf life is limited only by the drug stability and/or by opening of the storage vessel and introducing air and other impurities therein. One change has been in the form of a pre-filled and/or cartridge syringe in which a cylindrical drug chamber is pre-filled with a drug and sealed with a piston with an opening to receive a piston rod from the syringe at one end. However, the drug shelf life is limited by the quality of the fill and the seal between the piston and the wall of the cartridge in the opening left for the piston rod to connect with the piston.
Except in the instance of current cartridge designs, the present technological method for injecting drugs includes filling of ampoules and vials in order to store the drug for a period of time and then filling of the syringes, when needed, from these ampoules and vials. Filling of ampoules and vials is the most labor intensive and, therefore, the most expensive part of the process. In order to fill ampoules and the vials, the pharmaceutical company has to set up the clean-room operations, purchase and set up specific equipment, maintain supply of ampoules and the vials, employ operators, administration, technicians, engineers, quality control and the quality assurance personnel dedicated to this process. Ampoules and vials have to be stored and, therefore, the warehouse space is required. Inspections, handling and shipping add to the cost of the final product by adding the manpower required to handle all these operations, rejects and damages, and the cost of extra storage, logistics and the shipping containers. And, in addition to all that, the syringes are needed to inject the drug.
Some of these issues have been addressed with pre-filled syringes. The pre-filled syringes do not need ampoules and vials, but are not very popular and common. The presently available pre-filled syringes cannot maintain sterility for a long time and, therefore, have a very short shelf life. The shelf life of the modern common pre-filled syringes is a couple of months if that much. The reason for that is that the syringe is not perfectly sealed and air, germs and bacteria can work itself in while the drug can leak out. Plastic is not an ideal material to store some of the drugs for an extended period of time. The extended plunger of the pre-filled syringe could be accidentally pushed in or pulled out changing the volume of the drug inside or letting the air in. Pre-filled syringes cannot be shipped far unless specially designed containers are used (expensive). Therefore, pre-filling has to be done locally by qualified personnel just before the distribution. This option requires the qualified personnel and the necessary equipment to be present and one still cannot store it for any extensive period of time. Therefore, it cannot be pre-filled in advance at a medical production facility adding to the high cost of shipping.
All above adds to the logistics and the expense of the drug manufacturing process. Such shortcomings are even more appreciated when considering situations such as mass vaccinations, personal insulin injections, on-location pain relievers for the military, in sporting events and remote areas. A storage vessel easily convertible into a syringe without the shortcomings discussed above would solve these problems.
Thus, the need exists for a way to provide a storage vessel that easily converts into a syringe.